1. Field of the Invention
This invention relates generally to a method of assignment of user certificates/private keys in a token enabled public key infrastructure (PKI) system and, more particularly, to a method and computer program for creation, transmission, assignment and management of encryption, signature and role certificates/private keys in a token enabled PKI system.
2. Discussion of the Related Art
For centuries individuals, governments, and business entities have searched for mechanisms and techniques whereby sensitive information may be transmitted to authorized parties over long distances and still remain secure. The problem faced by the foregoing entities is how can information be sent to the individual or entities that require it and still be assured that unauthorized parties may not be able to comprehend the transmitted information should they intercept it. Early methods of securing information have employed scrambling techniques, lookup tables, substitution ciphers, and code books in which letters or terms would be substituted for the original letters and terms in the information. These techniques frequently required that both the sender and receiver of information have access to the same “code book.” One danger in such a technique is that the code book would fall into unauthorized hands.
In the early twentieth century, and in particular during World War II, code books were replaced by electromechanical cipher machines. Both the sender and receiver would have an identical cipher machine used to encrypt and decrypt messages sent. In order to make it more difficult to decrypt these messages the cipher machines have the ability to change the cipher used in a message or change the cipher used for every few words within a message. In order to accomplish this the cipher machine would need to know the initial state or key utilized to encrypt the message.
In recent years cipher machines have been replaced by digital encryption algorithms in which both the sender and receiver have an identical copy of the digital encryption algorithm and a common key used to encrypt and decrypt messages. Both the encryption algorithm and key are held secret by both the sender and receiver.
More recently another encryption technique has been developed in which two separate keys are used for encryption and decryption. A public key is transmitted freely to whoever requires it and is used to encrypt messages for a particular receiver. The receiver would have an associated private key which may be used to decrypt the message encrypted with the associated public key. For each public key there is only one private key and for each private key there is only one public key. When sending a message to several recipients it is necessary to have each recipient's public key. The message would then be separately encrypted using each recipient's public key and transmitted to that particular recipient. Therefore, if ten separate entities are to receive the same message, ten separate messages would be transmitted with each message encrypted with individual's public key. With the advent of the Internet, such a public key infrastructure has gained significant acceptance as discussed in request for comments number 2459, by Housley et al., entitled “Internet X.509 Public Key Infrastructure”, herein incorporated in its entirety by reference.
In addition to the need for the encryption and decryption of messages, with the advent of electronic mail and the Internet a need has developed for a secure mechanism to indicate approval and acceptance by an individual. In the past an individual would typically show his approval or acceptance of such items as a contract or an order via a handwritten signature, a stamp, or a seal which would only be held by that individual. Anyone else that attempted to imitate such a signature, stamp, or seal would be subject to criminal penalties. With the advent of electronic mail and the Internet, a need has arisen to take advantage of the ease and speed of electronic mail to indicate, by a person or entity with proper authority, approval or acceptance of a contract or purchase. This has come to be known as a digital signature in which an individual may digitally sign a document.
This digital signature capability has been implemented using the same public key infrastructure previously discussed. However, instead of an entire document being encrypted, the document itself is passed through a one-way hashing algorithm that produces a small document, referred to as a digest. This digest is then encrypted using the individual's private key, also known as a private signing key, and is appended to the document. The receiver of the document can verify the authenticity of the digital signature (digest) by stripping the signature from the document and recomputing the hash function on the document to generate an as received digest. Using a public signing key, included in the document or previously received, it is possible to decrypt the digest of the document and compare it to the digest as received. If the two digest match, then the signature is authenticated. Therefore, using the aforementioned public key infrastructure it is possible to both encrypt and decrypt messages as well as digitally sign documents.
However, in the aforementioned public key infrastructure, several limitations exist. One such limitation is in order for a group of individuals or entities to transmit and receive the encrypted messages each individual must have created a key pair having a public key and a private key. Further, each individual or entity in a group is also required to have a separate public signing key and a private signing key in order to digitally sign documents. In order for other members of the group to be able to decrypt messages received it is necessary for members of the group to exchange key pairs including the private key. This may be necessary when a member of the group is not in the office due to illness or travel. Where such an exchange of key pairs does not take place, when an urgent encrypted message comes into, for example, the office of finance, human resources, or an engineering group in the corporation, only the person holding the private key may decrypt the message. When that person is unavailable, that message will not be decrypted and a prompt response will not be received by the sender. However, when key pairs are exchanged by members of a group, then all members who possess an individuals private key may decrypt all messages sent to that person, regardless of the nature the message or its sensitivity. This creates significant problems for businesses that need to respond quickly to customer requests and in which customer confidences must be maintained. This may most acutely be seen in law offices, medical offices and the military where delay in delivering a response may be very costly. Further, it is cumbersome for a large group of individuals or entities to exchange key pairs with one another. For example, where group contains 30 individuals, a total of 30 times 30, or 900 exchanges of key pairs must take place in order for anyone in the group to be able to decrypt any message received by any other member of the group.
Another limitation that exists deals with security and portability of certificates/private keys. Typically, certificates/private keys assigned to users have both private and public keys with each stored on a computer. These certificates/private keys are often limited to usage in those computer systems in which they are stored. Therefore, if a user desires to use another computer system he must move his certificates/private keys to that system. Further, personal computers connected to the Internet have proven to be vulnerable to infiltration and damage by unauthorized parties. Therefore, if private and public encryption and signature certificates/private keys are stored on a personal computer which is directly or indirectly connected to the Internet, it is possible to copy the certificates/private keys and with some effort to determine the passphrase required to use the certificates/private keys.
Still another limitation to these certificates/private keys is that generating a new certificate/private key may either only be done by a security officer where high security is desired or done at a remote computer and downloaded to the user's computer with a password providing security. The use of a security officer is expensive and time consuming since the employee must setup an appointment, meet the officer, confirm his identity and then receive the certificate/private key. The downloading of a certificate/private key with only password security is risky particularly when a type of program known as a Trojan horse is used. This “Trojan horse” may intercept or access the certificates/private keys stored on the computer system for transmission to an unauthorized party.
A further limitation exists with the methods used to securely transport certificates/private keys to a User. In the typical PKI architectures, a unique X.509 private key and key encipherment certificate is issued to each server platform. This is used to create a Secure Socket Layer (SSL) session between the server platform and the client platform, so that all data transferred between these two platforms are encrypted and secure. However, a major security limitation exists because the so called last “6 inches” of the data path is not encrypted or secure; i.e., storage of the private key may be done while the key is in plain text and not yet re-encrypted.
Therefore, the client platform is a major point of vulnerability. Malicious code, such as viruses or Trojan horses, running surreptitiously on the Client Platform, could corrupt, replace, or intercept data being transferred between a server platform and the destination storage medium.
Therefore, what is needed is a method and computer program in which certificates/private keys of all types may be created, transmitted and stored in a secure manner. This method and computer program should not require a security officer or other person to provide security for the verification of the user's identity or the creation or downloading of any certificates/private keys. Further, this method and computer program should be secure against viruses or “Trojan horse” type viruses that may be present on the computer system being accessed by the user.